Expansion bolts - through hole applications

This innovative product replaces large fitted or interference fit bolts, no modifications required. Fast, safe and easy installation and removal.

Superbolt Expansion bolts (EBs) for through hole applications utilize a six piece system. The small end tensioner supplies the large force required to draw the tapered stud into the expandable tapered sleeve. As the tapered sleeve expands, a large radial force is exerted in the coupling through holes. The large end tensioner creates additional clamping force on the joint and is also used for easy removal of the tapered stud. Once the tapered stud is extracted, the sleeve collapses for easy removal.

Expansion bolts are made-to-order. Depending on your application, coating and special materials are optional. The team at Nord-Lock Performance Services will work with you to find the optimum solution. Contact your local Nord-Lock office if you wish to learn more about this solution.

Download the Expansion Bolt brochure here



  • Easy: Loose fit sleeves (up to .010″ – .020″ in the through-hole) are easily inserted even in holes misaligned due to rotation. Only hand tools are required for installation and removal.
  • Fast: Tightening requires only minutes per assembly.
  • Safe: Eliminates the need for special high powered tools and bolt deep freezing. Torque required is usually under 100 ft-lbs. Entire assembly requires only hand tools.
  • Economical: Saves money over alternative solutions in time and tooling. No need to ream/hone the bolts as normal machine precision is sufficient. Additionally, for precise alignment as little as two Expansion Bolts can be sufficient. Loose fit through-bolts with MJT tensioners, can be used in the remaining holes.
  • Reusable: The split sleeve springs back to original size, use after use. Compared to the close tolerance solid sleeves found in other systems, the loose fit split sleeve is much less likely to hang up during removal.
  • Generates axial and radial force simultaneously. Easier to “pull together” coupling halves.
  • No reaming/honing required: Only line boring of holes is necessary.
  • No coupling face machining is required (where the nuts seat). The multi-jackbolt design compensates for small variations in perpendicularity of the spotface to the hole centerline.
  • Eliminate finish machine of sleeves on site: Generous sleeve expansion permits finish machining in advance.


How they work:

Expansion Bolt pieces


  1. Slide split tapered sleeve (2) onto the tapered stud (1) and place together in the bore.
  2. On side A, place spacer (3) in the bore to center split sleeve between the split line.
  3. On side A, slide washer over the tapered stud (1) and screw on the tensioner (4) by hand.
  4. Tighten jackbolts stepwise according to tightening procedure.
  5. On side B, slide hardened washer over the tapered stud (1) and screw on the tensioner (5) by hand.
  6. Tighten jackbolts stepwise according to tightening procedure
  7. Verify tensioner torque on side A.



  1. According to removal procedures, loosen the jackbolts on side A stepwise and unscrew the tensioner (4) by hand.
  2. Tighten several jackbolts on side B further, in order to release the tapered stud (1) off the tapered sleeve (2).
  3. Unscrew the tensioner (5) by hand.
  4. Remove tapered stud (1), tapered sleeve (2) and spacer (3) from the bore.

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